1. Field of the Invention
The present invention relates generally to stump grinders and, more particularly, to a stump grinder having an automatic depth control system.
2. Description of the Related Art
It is known to provide a stump grinder for grinding undesirable tree stumps. Typically, a stump grinder includes a frame, an engine or other drive mechanism such as a belt tension engagement mounted to the frame, a cutting assembly having a boom pivotally secured to the frame, and a rotatable cutting wheel operatively supported by the boom and driven by the engine. The stump grinder also includes an actuating assembly to move the stump grinder and/or cutting assembly relative to the stump. Such actuating assemblies are typically hydraulic in nature, but may also be pneumatic, electronic, or mechanical. The stump grinder further includes a control system to control the direction and rate of movement of the actuating assembly. Such control systems are typically electronic in nature, but may be hydraulic, pneumatic, or mechanical.
During removal of a tree stump from a landscape, an operator directs the movement of the actuating assembly through the control system to cause the cutting assembly to engage a portion of the stump. As the cutting assembly engages the stump, the operator will typically laterally advance or feed the rotatable cutting wheel across an upper surface of the stump, grinding away a top portion of the stump. Upon completion of a lateral pass across the stump, the operator will direct the cutting assembly in a downward manner through the control system to engage the top surface of the stump and once again direct the rotatable cutting wheel across the upper surface of the stump in a lateral motion. This process is repeated until the stump is completely ground to an acceptable depth, which is typically below a grade of the landscape. Thus, the manner in which the operator controls the actuating assembly through the control system will directly affect the rate at which the cutting assembly will grind a stump.
Accordingly, the productivity of the stump grinder is dependent on the operator to maintain an appropriate rate of speed and depth of the cutting assembly into the stump. Placing the cutting assembly at too great a depth into the stump will slow the rotation of the cutting assembly and overwork the engine, which may result in engine stall or part failure. When the engine stalls or a part fails, the stump grinder may become plugged or otherwise inoperable. As a result, the stump grinder has to be unplugged or serviced, the engine restarted, and then redirected at the stump. This is a relatively time consuming and labor intensive process, resulting in higher costs, which is undesired. Conversely, placing the cutting assembly at too little depth into the stump will under-work the engine causing a more time consuming process than otherwise necessary, resulting in a loss of productivity and higher operational costs.
Conventionally, maintaining a balance between overworking and under-working the engine is based on an operator's sensory perception of a working stump grinder. By way of example, an operator makes a depth adjustment based on engine sound or vibration felt in the controls. However, an operator's sensory perception is highly subjective relative to one's skill/experience, ambient conditions, stump condition, etc. and therefore subject to a loss of maximum efficiency.
While known stump grinders have generally worked for their intended purpose, there remains a need in the art for stump grinders that provide improved output efficiency. More specifically, there is a need in the art to provide a stump grinder that overcomes the disadvantage of overworking or under-working the engine as a result of improper depth placement of the cutting assembly into a stump during operation. Therefore, there is a need in the art for a stump grinder that overcomes the above disadvantages by having a control system that automatically sets the depth of the cutting assembly during operation.